Two stroke cycle internal combustion engines conventionally have cylinders ported to the crankcase for receiving a combustible charge, the crankcase on small one cylinder engines such as used in radio controlled model airplanes being valved to admit combustible fuel charge from a carburetor on the upstroke of the piston, with attendance creation of partial vacuum in the crankcase, and to seal the crankcase on the downstroke of the piston thereby increasing pressure in the crankcase and forcing combustible mixture into the cylinder. Cyclic pressure produced in the crankcase may be utilized through means of a crankcase tap to drive a diaphragm pump to supply fuel to the engine carburetor, such means being shown in U.S. Pat. Nos. 3,967,606 and 4,184,811, in conjunction with control devices for regulating pump output to prevent wide variations in fuel pump output from occurring as engine speed varies. For example, a simple diaphragm pump driven by engine crankcase pulsations may deliver fuel to the engine carburetor at a desirable level of six ounces per square inch pressure at engine idle, but provide sixty-four ounces per square inch pressure at full throttle. For ideal engine operation, fuel pressure at the carburetor should be nearly constant throughout the range of engine speeds and operating conditions where non-metered-non-aspirated carburetion is utilized.